A shipbuilding company making diesel-powered freighters was having problems with their throttle control system. Vibrations and a harsh operating environment were introducing play into throttle linkages in the engine room, reducing accuracy.-The solution involved the Uhing "rolling-ring" drive, a mechanical device that smoothly translates rotary motion into linear motion.

The installed system has a stroke length of 80 mm for the throttle and works despite temperatures that soar to 158F. It tightly couples the throttle controls on the bridge to engine fuel settings and is unaffected by vibrations. The rolling-ring drive does not use a threaded shaft, so there's no place for

dirt and oil to accumulate. And the lack of threads means there is little wear that might inject play into the throttle control. The drive also has no backlash, so rotary motion from the shaft is immediately converted to a linear output, even when put in reverse.

A watertight casing encloses the throttle linkage in the engine room of a freighter. The throttle-adjustment rod controls engine speed, sliding in and out of a gasketed hole to do so. Moving the master throttle on the ship's bridge transmits a potentiometer signal to the electric motor in the engineroom throttle controller. The motor turns the required amount, rotating the rolling-ring driveshaft which is fixed in place linearly, causing the drive itself to move left or right along the shaft. The drive also moves a toothed profile over a gear on the throttle rod and thereby controls the location of the throttle rod. A transmitting potentiometer on the throttle rod detects the rod's actual location and relays it to the bridge so the crew can confirm that the throttle setting and actual throttle position are the same.